Polygenic inheritance - A continuous, rather than discrete, set of traits that are influenced by many genes. Prolactin - A peptidehormone that induces lactation and parental care. Search images - Key stimuli used to find food and other resources.

On the other hand, polygenic inheritance, epistasis , gene interaction, operons, and regulatory circuits all involve a many-to-one relationship between genotype and phenotype. Wheat color provides a good example of polygenic inheritance, the contribution of more than one gene to a single trait.

Quantitative variation is usually due to polygenic inheritance in which the additive effects of two or more genes influence a single phenotypic character. Discrete characters, such as flower color, are usually determined by a single locus with different alleles that produce distinct phenotypes.